John Carney, the director of Knightley's 2013 musical romantic comedy Begin Again, had some not-so-flattering-words for the actress during an interview with the Independent, explaining that he was "disenchanted" after working with her on the film.
"I didn't enjoy that experience of paparazzi and fabulous openings. The movie star world is not something that ever appealed to me," the Irish director said of working on the movie in America. "I like working with actors and I wanted to come back to what I knew and enjoy film-making again – not that I didn't enjoy Begin Again but Keira has an entourage that follow her everywhere so it's very hard to get any real work done."
Carney, whose latest film is Sing Street, further said that Keira's singing and guitar playing skills made it hard to make the film's music "seem real."
"And as much as I tried to make it work I think that she didn't quite come out as a guitar-playing singer-songwriter," he said.
He continued of Begin Again, "I learned that I'll never make a film with supermodels again."
Meanwhile, Carney had high praise for the film's male leads – Mark Ruffalo and Adam Levine – even calling the Maroon 5 frontman "a joy to work with." He said actors have to be unafraid to be uninhibited on camera, and claimed that two-time Oscar nominee Knightley doesn't have that quality.
"Keira's thing is to hide who you are and I don't think you can be an actor and do that," he explained, later adding that, "I like to work with curious, proper film actors as opposed to movie stars. I don't want to rubbish Keira, but you know it's hard being a film actor and it requires a certain level of honesty and self-analysis that I don't think she's ready for yet and I certainly don’t think she was ready for on that film."
Knightley began acting as a child, and has earned Oscar nominations on two occasions: first for Atonement in 2007, and later for 2014's The Imitation Game. In addition to several other Golden Globe nods, Knightley has also starred on Broadway and was named No. 2 on Forbes annual highest earning actresses list in 2008.